... algebra¹

Note that an $\mathbb{N}$ -graded algebra may be viewed as an $\mathbb {Z}$ -graded or $\mathbb{Z}/2\mathbb{Z}$ -graded algebra in a natural way.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

... ²

It seems that the definition here is not the best one for general schemes. Hochschild homology may be better. But since we have not done (co)homological arguments, we postpone this topic later.

.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.